SemiLEDs Launches FlipChip LED Series
SemiLEDs Corporation has announced sampling and volume availability of the first in its new Enhanced FlipChip, or EF, LED series. The series launches with the EF-B40, a blue 40-mil flip chip that the company says simplifies packaging and integration by eliminating wire-bonding.
SemiLeds adds that the series offers improved lumen-density while enabling packagers to use standard surface mount assembly techniques.
Mark Tuttle, general manager for SemiLEDs Optoelectronics explained, "SemiLEDs'unique flip chip approach combines a sapphire front surface and proprietary back side architecture that provides the electrical contacts exclusively on the bottom of the chip, making it fully compatible with chip-on-board (COB) surface mount processes. Eliminating wire-bonds also lowers the profile of the chips, and allows them to be placed more closely together, which results in higher lumen-density and reduces the complexity of the optics. The EF series is an ideal platform for COB assemblies, or really for any approach that calls for either secondary optic design or high-density mounting."
Flip chip construction presents what was originally the bottom sapphire layer in a horizontal LED structure as the top surface of the chip. By flipping the chip, the electrical pads become part of the bottom of the device rather than running bonding wires from the top surface of the chip down to the package or board. The delicate areas of the chip are therefore protected by the clear sapphire layer and by eliminating wire bonds, both reliability and overall design flexibility of the packaged device are increased. In addition, individual chips may be more closely mounted. The nearly continuous light emitting surface, unbroken by gaps, bonding wires, or top electrodes, can simplify the mounting and mixing requirements of the optics, producing smooth lighting effects. In addition, in a flip chip structure, the heat-generating junction is positioned adjacent to the substrate, increasing thermal conductivity and allowing improved device performance at high currents.
The EF-B40 is available in wavelengths from 445 to 460nm, with outputs of up to 300 lumens at 1A as a packaged emitter. The SAC compatible chips are offered with standard Au bonding pads, or are available with an AuSn option to further reduce thermal resistance and add to system reliability. A 140-degree viewing angle makes the EF ideal for general and commercial lighting, while the lowered profile addresses the application needs of LED backlight, smartphone flash or LED projector.
